# 集合
a = {"a", "b", "c", "1"}
b = {"a", "c", "d", "2", "3", "1"}
c = {"a", "b"}
# S | T
print(a | b)
# S - T
print(a - b)
print(a - c)
# S & T
print(a & b)
# S ^ T
print(a ^ b)
# S <= T 或 S < T
print(a <= b)
print(c <= a)
print(c < a)
# S >= T 或 S > T
print(a >= c)
print(a > b)

a |= b
print(a)
a -= b
print(a)
print(b)
a &= b
print(a)
a ^= b
print(b)
print(a)

print("a" not in a)
a.remove("a")
a.add(123)
print(a)
